Dry hydrant strainer with strainer hole pattern for achieving uniform flow rates

ABSTRACT

A strainer for use with a dry hydrant having a fluid inlet includes an inlet tube having a first end and a second end, the first end being substantially capped, and the second end being connected to the dry hydrant fluid inlet. A plurality of apertures are formed in the inlet tube and are disposed between the first end and the second end. The apertures are disposed in a substantially v-shaped pattern, whereby an apex of the substantially v-shaped pattern is spaced proximal to the second end. In one embodiment of the present invention, the apertures spaced proximal to the first end of the inlet member have diameters greater than diameters of the apertures spaced proximal to the second end of the inlet member. In operation in a dry hydrant system, the strainer provides for uniform suction zone throughout the inlet pipe, and provides uniform fluid drafting flow.

This application is a division of application Ser. No. 08/561,185 filedNov. 21, 1995, now U.S. Pat. No. 5,650,073.

TECHNICAL FIELD

This invention relates generally to dry hydrants, and more particularly,to a dry hydrant strainer for providing uniform suction and fluid flowthroughout the strainer during operation of the dry hydrant.

BACKGROUND OF THE INVENTION

Dry hydrants are a type of fire service hydrant for use where there isno source of pressurized water. For example, in rural areas where thereis no centralized water service, water for fire fighting is commonlydrawn from lakes, ponds, cisterns or the like. Typically, a tanker truckwill draw water from a nearby body of water using a flexible hose fittedwith a strainer to prevent debris from being drawn into the hose. Thetanker will then travel to the site the fire, where a pumper truck drawswater from the tanker to fight the fire.

To simplify and speed up the process of pumping water from lakes andponds or the like, many areas have installed dry hydrant systems. A dryhydrant system usually includes a length of pipe having one end disposedbelow the water line of a body of water and the other end disposed at ornear the shoreline. In these arrangements, a length of polyvinylchloride(PVC) pipe is laid in a trench dug from the shoreline of a body of waterto enable one end of the pipe to be disposed at a predetermined fixeddepth in the water. The other end of the pipe is connected via a 90°elbow to a vertical standpipe. The standpipe is provided with a couplingwhich enables a standard fire hose to be connected to the standpipe todraw water through the dry hydrant to a tanker truck.

Typical strainers used with dry hydrants or dry hydrant piping systemsconsist of a pipe with uniformly sized holes drilled along its length.Such strainers either have holes drilled completely around thecircumference of the pipe or only partially. Strainers with holesdrilled around the complete circumference are generally positionedvertically in the lake or pond. Strainers with holes only partiallyaround the circumference are placed horizontally in the body of water;furthermore, in such an arrangement, the holes face the bottom of thelake or pond. Both of these strainers usually contain a capped end and asuction end to which the PVC piping system is attached. Thus, when thetanker truck draws water via the coupling and PVC piping system, thewater is drawn through the holes of the strainer.

In such an arrangement, the strainer must be properly positioned at thecorrect depth in the body of water. If placed indiscriminately, thestrainer may draw debris, leaves or mud from the bottom of the pond oflake which will clog the strainer and diminish the flow of water to thetanker. For example, after a storm, the bottom area under a horizontalor vertical strainer may often be unsettled and shodden with debris. Insuch circumstances, or even when a strainer is haphazardously positionedin a lake, the suction created by the tanker pump may draw such debrisand possibly clog the strainer, the piping system, or even ruin thepump. Such complications waste valuable time and may prevent the savingof property and lives.

In other circumstances, both the horizontal strainer and the verticalstrainer may be too close to the surface of the water. Such instancescommonly occur in areas with low tides, dry seasons, or periodic changesin water level, such as lakes, ponds, seas, bays, or rivers. When thewater level is low and too close to the strainer, the suction created bythe tanker pump often creates whirlpool vortices. Such vortices causeair to enter the strainer, which in turn causes pump cavitation, andultimately, pump failure. This problem also impairs the ability of firefighters to save property and lives.

The above described problems generally occur because dry hydrantstrainers typically employ a uniform drill pattern and constant holediameter. The size, location, and number of the holes creates aconcentrated zone of low pressure near the suction end of the strainer.Thus, the holes near the suction end of the strainer experience highsuction and high water flow rates, while those near the capped end ofthe strainer experience very little suction and low water flow rates.Because the high suction and high flow rates are concentrated in onearea, the low pressure area and zone of accelerating water outside thestrainer extend far away from the outer surface of the strainer. Thisphenomena dramatically increases the likelihood of whirlpool vorticesand the drawing of debris. The hole design of these strainers alsocreate uneven backflushing when reversing flow through the strainer inan attempt to remove debris.

The previous described problems associated with current dry hydrantstrainers limit their range of use. Sources of available water are oftenfull of debris and may be very shallow. Because of the above identifiedproblems of current strainers, dry hydrants may not be used in somebodies of water. Thus, tanker trucks must travel further distances toreceive water from deeper or less debris shodden waters. The previouslydescribed constraints of current dry hydrant strainers has created aneed for a solution.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a dry hydrantstrainer which draws a substantially uniform fluid flow rate through theholes located along the length of the strainer.

Another object of the present invention is to provide a dry hydrantstrainer which discourages the creation of whirlpool vortices and ismore useful in shallow waters than previous strainers.

Another object of the present invention is to provide a dry hydrantstrainer which discourages the drawing of debris to the strainer.

Still another object of the present invention is to provide a strainerwhich backwashes evenly when attempting to remove debris from thestrainer through reverse flow.

Yet another object of the present invention is to provide a dry hydrantstrainer which is readily adaptable to a dry hydrant piping system.

Another object to the present invention is to provide a method ofstraining fluid through a dry hydrant strainer which is safer, morereliable, and more efficient than past methods of straining.

According to the present invention, the foregoing and other objects areobtained by dry hydrant strainer that includes a hollow pipe ofpredetermined length with a suction end and a capped end. The pipe has apattern of selectively sized and spaced holes located along its length.When the strainer is located in a fluid body, and the suction end isconnected to a source of suction, fluid is drawn through the suction endsuch that a substantially uniform fluid flow rate develops through theholes located along the length of the pipe.

In accordance with another aspect of the invention, the selectivelysized and spaced holes progressively increase in diameter along thelength of the pipe.

In accordance with another aspect of the invention, the selectivelysized and spaced holes extend partially around the circumference of thehollow pipe.

In accordance with yet another aspect of the present invention, theselectively sized and spaced holes form a substantially v-shaped patternalong the length of the pipe.

In accordance with yet another aspect of the present invention, thelength of the pipe is located substantially horizontal in the fluidbody, and the v-shaped pattern substantially faces the bottom surface ofthe fluid body.

In accordance with a further embodiment of the present invention, thelength of the pipe is located substantially vertical in the fluid body.

According to the present invention, the foregoing and other objects andadvantages are obtained by a method of dry hydrant straining with theaforementioned dry hydrant strainer comprising the steps of: placing thepipe in a fluid body; applying a predetermined suction to the suctionend by a source of suction such that the fluid is drawn through thesuction end, wherein a substantially uniform fluid flow rate developsthrough the holes located along the length of the pipe.

According to the present invention, the foregoing and other objects andadvantages are obtained by a dry hydrant system using the aforementioneddry hydrant strainer, where the suction end of the dry hydrant straineris in fluid communication with a piping system. The piping systemincludes an above ground unpressurized hydrant pipe. The unpressurizedhydrant pipe includes a coupling adapted for connection to a fireservice apparatus.

Still other objects and advantages of the present invention will becomereadily apparent to those skilled in the art from the following detaileddescription, wherein I have shown and described only the preferredembodiment of the invention. As will be realized, the invention iscapable of other and different embodiments, and its several details arecapable of modification in various obvious aspects, all withoutdeparting from the invention. Accordingly, the drawings and descriptionsare to be regarded as illustrative in nature, and not restrictive.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a dry hydrant incorporating features of thepresent invention;

FIG. 2 is a side view of the dry hydrant strainer of FIG. 1

FIG. 3 is a flat plan view of the dry hydrant strainer of FIG. 2,depicting the pattern of apertures in the strainer; and

FIG. 4 is a side view of an alternative embodiment of the dry hydrantstrainer.

DESCRIPTION OF THE DRAWINGS

A dry hydrant system (10) incorporating features of the presentinvention is depicted in FIG. 1, wherein piping (14) is partiallysubmerged, and extends in a horizontal portion (20), in a fluidreservoir (18), and transitions through a right-angled portion (22), toa vertical portion (24) such that the piping (14) emerges through theground (26) at a convenient location for use. In a preferred embodiment,the piping (14) is circular in cross-section, formed frompolyvinylchloride (PVC), and comprises a plurality of pipe sectionssecured together at joints.

However, in alternative embodiments of the present invention, the pipingmay assume a variety of cross-sectional shapes, including but notlimited to square, rectangular, ovaloid, hexagonal, or triangular. Inalternative embodiments, the piping (14) may be formed from varioustypes of plastics, metals, composites, or any combination thereof.Although in a preferred embodiment, the piping (14) comprises a numberof pipe sections, in other embodiments, the piping (14) may be formed asa unitary structure, or may comprise any number of sections. Inaddition, the layout of the pipings (14) is not limited to thehorizontal (20) and vertical (24) arrangement depicted in FIG. 1. It isunderstood that one skilled in the art may arrange the piping (14) in amanner that will efficiently transfer fluid from the reservoir (18) to adesired location in accordance with the unique features of the setting.

The piping (14) is normally in an unpressurized condition, therebynecessitating the use of suction pump (12) or some other form of suctionmeans to pressurize the piping (14) in order for the dry hydrant system(10) to operate. In a preferred embodiment, as depicted in FIG. 1, thesuction pump (12) is connected to the hydrant piping (14) at a locationthat makes the suction pump (12) convenient to use, in this case, aboveground (26) near the reservoir (18). The suction pump (12), in turn, hasan outlet (28) through which a hose (not shown) or any other fluiddelivery device may be attached to deliver fluid to an intended target.

In the embodiment of the dry hydrant system (10) depicted in FIG. 1, afire truck carrying a suction pump (12) provides pressurization to thepiping (14). However, in alternative embodiments, any type ofconventional pump, suction device, or any other means for producing apressure differential may be used in conjunction with the dry hydrantsystem (10). These pumps may be mechanically, manually, or electricallyoperated, including combinations thereof. In a preferred embodiment, thesuction pump (12) is also capable of reversing the fluid flow in orderto backflush the piping (14) and strainer (16).

Although in a preferred embodiment, the suction pump (12) is locatedabove ground (26) near the reservoir (18), in alternative embodiments,the suction pump (12) may be disposed at any convenient location,including but not limited to, any location along the lengths of piping14. The only requirement is that the pump selected have the ability toproduce a pressure differential great enough to draft the fluid from thereservoir (18), and deliver the fluid at a sufficient pressure at anoutlet. In alternative embodiments, multiple mumps may be used toachieve the desired pressure differential, or in addition, to deliverthe fluid to a plurality of piping branches leading to a plurality ofoutlets.

As depicted in FIG. 1, the portion of the piping (14) that is submergedin the reservoir (18) terminates with a fluid inlet (30). It is throughthe fluid inlet (30) that the reservoir fluid enters the piping (14)when the fluid is subjected to pressure differentials produced by thesuction pump (12). Connected to the fluid inlet (30) is the dry hydrantstrainer (16).

In a preferred embodiment, the strainer (16) is a pipe with a circularcross-section, and is oriented horizontally with the horizontal portion(20) of the piping (14). The strainer (16) is substantially capped at afirst end (34 with a hemispherical cap (36), and is connected to thefluid inlet (30) at a second end (38).

In alternative embodiments of the present invention, the strainer (16)may be formed from inlet members having a variety of cross-sectionalshapes. Although in a preferred embodiment, the cap (36) is a separateelement and hemispherical in shape, in alternative embodiments, anymeans for capping the first end (34) of the strainer (16) may be used,including welding or screwing on caps of various shapes and materials,or even forming a cap which is unitary with the inlet member. Inaddition, the cap (36) does not necessarily have to completely cap thefirst end (34), since in a preferred embodiment, a plurality ofapertures (32') are formed in the cap (36) in order to allow some fluidflow through the cap. The first end (38) of the strainer (16) may beconnected to the inlet (30) of the piping (14) using conventional meansknown in the art for joining two such sections.

As depicted in FIGS. 2 and 3, the strainer (16) contains a plurality ofapertures (32) with diameters that are sized, in general, such thatfluid may pass through each aperture (32), but which are small enough toprevent various types of debris from entering the fluid inlet (30), thusserving as a "strainer". The apertures (32) may be formed by boringthrough the strainer (16), or may be formed during the manufacture ofthe strainer (16) itself (e.g., injection molding).

In a preferred embodiment of the present invention, the apertures (32)form a v-shaped pattern (40) in the strainer (16) such that the apex(42) of the v-shaped pattern (40) is spaced proximal to the second endof the strainer (16). The v-shaped pattern (40) is disposedsubstantially on the underside (44) of the strainer (16). The absence ofthe apertures (32) from the upper-side (46) of the strainer (16) isnecessary to conform with the safety requirements mandated by theNational Fire Protection Association (or to conform with otherapplicable governmental and/or industry standards) in order to preventthe possibility of whirlpools forming near the strainer (16).

As depicted in FIG. 3, the v-shaped pattern (40) further comprises aplurality of aperture groupings (48), wherein the layout of apertures(32) in each grouping (48) defines a height dimension (50) and widthdimension (52) that is consistent within that grouping (48). To form thev-shaped pattern (40), the groupings (48) are centered about thelongitudinal axis (54) of the strainer (16) and extend to the second end(38) of the strainer. The juxtaposition of the groupings (48) havingthese descending heights roughly forms the desired v-shaped pattern(40). In addition, apertures (32') may be disposed about the strainercap (36), if necessary, to provide for extra fluid entry. As will benoted later, the height (50) and width (52) of each grouping (48), andthe number of groupings (48), may depend on characteristics unique tovarious dry hydrant systems and surroundings.

In addition, the diameters (56) of the apertures (32) are preferablysubstantially consistent within each grouping (48) , but are notnecessarily consistent from one grouping (48) to another. The apertures(32) in groupings (48) near the first end (34) of the strainer (16) haveaperture diameters (56) that are greater than those apertures (32) nearthe second end (38) of the strainer (16). Specifically, as depicted inthe embodiment of FIG. 3, grouping A has aperture diameters (56) thatare smaller than grouping B, and grouping B has aperture diameters (56)that are smaller than grouping C, but groupings D-H have diameters thatare consistent. As will be noted below, the diameters (56) of theapertures (32) in each grouping (38) are dictated by some of the samefactors that help determine the height (50) and width (52) of eachgrouping.

In operation, the disposition of the apertures (32) in the v-shapedpattern (40), plus the use of apertures (32) of differing diameters(56), combine to provide uniform suction throughout the strainer 16.Otherwise, when the suction pump (12) is activated, the suction forcenear the second end (38) of the strainer (16), acting through a constantrectangular pattern of holes, would cause fluid to be drafted near thesecond end (38) of the strainer (16) at a rate greater than the fluiddrafted at the first end (34). This drafting imbalance causes unevenfluid flow about the strainer (16) and may result in a whirlpoolforming, thereby reducing the effectiveness of the entire dry hydrantsystem 10.

In the present invention, the layout of the apertures (32) in thev-shaped pattern (40) coupled with the use of apertures (32) of varyingdiameters (56), results in an even distribution of suction forcesthroughout the strainer (16), thereby delivering continuous fluid flowinto the fluid inlet (30). As is known in the art of fluid dynamics,there is a mathematical relationship (i.e., Bernoulli's Equation)between force applied to a fluid, fluid velocity, and cross-sectionalarea. Using that relationship, since the suction force at the second end(38) of the strainer (16) is greater than the suction force at the firstend (34), then in order to ensure that the velocity of the fluidentering the strainer (16) is uniform over the length of the strainer(16) according to this mathematical relationship, the cross-sectionalarea of openings in the strainer (16) along the longitudinal axis (54)of the strainer (16) must be greater near the first end (34) than thesecond end (38) of the strainer (16). In the present invention, thiscross-sectional area of the openings in the strainer (16) is achieved byvarying the diameters (56) of the apertures (32) in each grouping (48),the number of apertures (32) in each grouping (48), and the height (50)and width (52) of each grouping (48).

As will be apparent to one skilled in the art, the layout of thev-shaped pattern (40), and the diameters (56) of the apertures (32)depend on a variety of factors, including, but not limited to, thesuction force created by the pump 12, the force generated at the fluidinlet (30), the length and cross-sectional area of the strainer (16),the density of the fluid being pumped, and the desired velocity of thefluid entering the inlet (30).

For exemplary purposes, the following table provides aperture diameters(56) and dimensions related to the groupings (48) in the v-shapedpattern (40) for one embodiment of the present invention as depicted inFIG. 3.

    ______________________________________                                                                            Aperture                                  Grouping # Columns # Rows    Diameter                                                                             Spacing                                   ______________________________________                                        A        10        6         0.25"  0.5"                                      B        4         8         0.3125 0.5                                       C        1         8         0.375  N/A                                       D        3         10        0.375  0.625                                     E        3         12        0.375  0.625                                     F        4         14        0.375  0.625                                     G        3         16        0.375  0.625                                     H        3         18        0.375  0.625                                     I        20        20        0.4375 0.625                                     J        9         16        0.5    0.625                                     ______________________________________                                    

The strainer (16) embodying features of the present invention providesfor many advantages over the prior art. The uniform suction and fluidflows associated with the strainer (16) reduces the reservoir depthnecessary above the strainer (16) by one foot. In addition, the depth ofthe reservoir necessary to use the strainer is reduced by half a foot.Therefore, a strainer (16) embodying features of the present inventionmay be used in fluid reservoirs having depths that might have preventeduse of the prior art strainer.

In another embodiment of the present invention, as depicted in FIG. 4,the strainer (16') is oriented in a vertical position. In thisembodiment, the apertures (32') are not disposed in a v-shaped pattern,but rather, are disposed continuously about the outer surface of thestrainer (16'). However, as with the preferred embodiment, the apertures(32') spaced proximal to the fluid inlet (30) have diameters (56') thatare smaller than the diameters (56') of the apertures (32') spaceddistal from the fluid inlet (30).

In alternative embodiments of the present invention, strainers embodyingfeatures of the present invention may contain the v-shaped pattern andhave apertures of consistent diameters, may not have the v-shapedpattern but have apertures of inconsistent diameters, or may have acombination of the v-shaped pattern and inconsistent diameters. Inaddition, alternative embodiments are not limited to a horizontal orvertical orientation of the strainer. In these embodiments, the strainermay also be positioned at various angles to improve fluid flow.

It will be readily seen by one of ordinary skill in the art that thepresent invention fulfills all the objects set forth above. Afterreading the foregoing specification, one of ordinary skill will be ableto effect various changes, substitutions or equivalents and variousother aspects of the invention as broadly disclosed herein. It istherefore intended that the protection granted hereon be limited only bythe definition contained in the appended claims and equivalents thereof.

I claim:
 1. A system for drafting fluid from a fluid reservoir, saidsystem comprising:(a) suction means for producing suction; (b) an inletsubmerged within said fluid reservoir, said inlet comprising:an inletmember having a first end and a second end, said first end beingsubstantially capped, said second end being connected to said suctionmeans; a plurality of apertures in said inlet member disposed betweensaid first end and said second end said apertures spaced proximal tosaid first end of said inlet member having diameters greater thandiameters of said apertures spaced proximal to said second end of saidinlet member, wherein said differences in diameters defines means forproviding a uniform suction zone throughout said inlet member; and (c)an outlet connected to said suction means, said outlet being capable ofdelivering said fluid upon activation of said suction means.
 2. A systemfor drafting fluid from a fluid reservoir, said system comprising:(a)suction means for producing suction; (b) an inlet submerged within saidfluid reservoir, said inlet comprising:an inlet member having a firstend and a second end, said first end being substantially capped, saidsecond end being connected to said suction means; a plurality ofapertures in said inlet member disposed between said first end and saidsecond end, said apertures being disposed in a substantially v-shapedpattern, whereby an apex of said substantially v-shaped pattern isspaced proximal to said second end, wherein said apertures spacedproximal to said first end of said inlet member have diameters greaterthan diameters of said apertures spaced proximal to said second end ofsaid inlet member, the difference in diameters defining means forproviding an even distribution of suction forces; and (c) an outletconnected to said suction means, said outlet being capable of deliveringsaid fluid upon activation of said suction means.
 3. A strainer for usewith a fluid pumping system, said fluid pumping system having an inlet,said strainer comprising:(a) an inlet member having a first end and asecond end, said first end being substantially capped, said second endbeing connected to said fluid pumping system inlet; and (b) a pluralityof apertures in said inlet member disposed between said first end andsaid second end, said apertures being disposed in a substantiallyv-shaped pattern, whereby an apex of said substantially v-shaped patternis spaced proximal to said second end, wherein said apertures spacedproximal to said first end of said inlet member have diameters greaterthan diameters of said apertures spaced proximal to said second end ofsaid inlet member, the difference in diameters defining means forproviding an even distribution of suction forces throughout thestrainer.
 4. A strainer for use with fluid pumping system, said fluidpumping system having an outlet, said strainer comprising:(a) an outletmember having a first end and a second end, said first end beingsubstantially capped, said second end being connected to said fluidpumping system outlet; and (b) a plurality of apertures in said outletmember disposed between said first end and said second end, saidapertures being disposed in a substantially v-shaped pattern, whereby anapex of said substantially v-shaped pattern is spaced proximal to saidsecond end, wherein said apertures spaced proximal to said first end ofsaid outlet member have diameters greater than diameters of saidapertures spaced proximal to said second end of said outlet member, thedifference in diameters defining means for providing an evendistribution of suction forces throughout the strainer.